Maize Genetics Cooperation Newsletter

maize gene review

Author: Alice Barkan, University of Oregon, Eugene, OR. USA 97403


Review: pending

Pub date: May 2009

Name: ppr4--pentricopeptide4

Chromosome -- unknown--

Function: rps12 trans-splicing

image of corn mutant

Summary: Encodes the chloroplast PPR4 protein required for trans-splicing the rps12-1 group II intron. The null allele of ppr4 (ppr4-1) is albino; and a weak allele (ppr4-2) is pale green. Both condition a non-photosynthetic, seedling lethal phenotype due to the failure to splice the rps12 mRNA. This splicing defect blocks the biogenesis of the plastid translation machinery, which in turn leads to the loss of all plastid-encoded proteins.

Images: mutant leaf colors depicted on a seedling leaf color scale

First reported: Schmitz-Linneweber et al. 2006.

Key Alleles

ppr4-1::Mu9; Mu9 insertion in the first exon. Ivory, seedling lethal phenotype. Mutants are smaller than wild type siblings.

ppr4-2::Mu1; Mu1 insertion in the first intron. Pale green, seedling lethal phenotype. Heteroallelic progeny of complementation crosses between ppr4-1::Mu1 and ppr4-2::Mu9 have an intermediate phenotype.

Gene Product

PPR4, localized to chloroplast stroma, specifically associates with the first intron of rps12 pre-mRNA. This intron is transcribed in segments.

Related loci

rps12; PPR4 is required for the rps12 trans-splicing reaction (Schmitz-Linneweber et al. 2006).

Not allelic to hcf7.


Schmitz-Linneweber C, Williams-Carrier RE, Williams-Voelker PM, Kroeger TS, Vichas A, Barkan A (2006) A Pentatricopeptide Repeat Protein Facilitates the trans-Splicing of the Maize Chloroplast rps12 Pre-mRNA. Plant Cell 18: 2650-2663. PUBMED

Links: MGDB: ppr4 NCBI: DQ508419 UniProt: Q1G1I8